Fig. 1From: Hip preserving surgery with concentrated autologous bone marrow aspirate transplantation for the treatment of asymptomatic osteonecrosis of the femoral head: retrospective review of clinical and radiological outcomes at 6 years postoperativelyMeasurement of femoral head collapse. Collapse extent is defined as the distance between the overlay circle and the collapsed femoral head (white arrow). a anteroposterior view. b lateral view (Sugioka view). a’ enlarged view of a b’ enlarged view of b Back to article page